During semiconductor manufacturing, a chemical mechanical polishing (CMP) process is used to planarize a surface of a semiconductor device. In some instances, the CMP process causes a gradient in a pattern density of the planarized surface to be formed across the planarized surface of the semiconductor device. The pattern density is a ratio of an area occupied by cells within a semiconductor device to a total area of the semiconductor device. In some instances, CMP processes result in dishing of the semiconductor device, meaning some cells of the semiconductor device are removed faster than other regions forming a gradient in the pattern density. The gradient is most pronounced near an exterior edge of the semiconductor device. Semiconductor devices which have a pattern density gradient exceeding a threshold value function improperly. To ensure a requisite number of functioning cells are formed in the semiconductor device, semiconductor devices are designed with dummy cells around an exterior edge where the pattern density gradient is most pronounced. These dummy cells increase the size of the semiconductor device without increasing functionality of the semiconductor device.
In another semiconductor device design process, a layout versus schematic (LVS) tool is used to compare a schematic design to a layout design. The layout design comprises a mask or masks having patterns formed therein which are used to form features of the schematic design. Once the LVS tool determines the layout design accurately corresponds to the schematic design, the dummy cells are inserted into the layout design to compensate for pattern density gradients. Following the insertion of the dummy cells, a design rule checking (DRC) tool determines whether the revised layout design violates any design rules, such as element size or spacing. If either the LVS tool or the DRC tool detects an error, the layout design is revised and the checking process restarts from the LVS tool.